Microfluidic devices may be used in a variety of applications to perform any number of microfluidic processes on particles.
In the fields of biotechnology, and especially cytology and drug screening, there is a need for high throughput sorting of particles. Examples of particles that require sorting are various types of cells, such as blood platelets, white blood cells, tumorous cells, embryonic cells and the like. These particles are especially of interest in the field of cytology. Other particles are (macro) molecular species such as proteins, enzymes and poly-nucleotides. This family of particles is of particular interest in the field of drug screening during the development of new drugs.
Methods and apparatuses for particle sorting are known, and the majority described in the prior art work in the condition where the particles are suspended in a liquid flowing through a channel network having at least a branch point downstream and are operated according the detect-decide-deflect principle. The moving particle is first analyzed for a specific characteristic, such as optical absorption, fluorescent intensity, size, or another suitable characteristic. Depending on the outcome of this detection phase, it is decided how the particle will be further handled. The outcome of the decision is then applied to deflect the direction of specific particle towards a predetermined branch of the channel network.
Of importance is the throughput of the sorting apparatus, i.e. how many particles can be sorted per unit of time. Typical sorting rates for sorters employing flows of particle suspension in closed channels are in the range from a few hundred particles per second to thousands of particles per second, for a single sorting unit.
In certain microfluidic processes, such as particle sorting, certain actuators used to actuate a process, such as separation of particles having a predetermined characteristic from particles that do not have a predetermined characteristic, may present drawbacks. For example, certain actuators may take up a relatively large amount of space on a microfluidic chip, limiting the efficiency with which actuators can be packaged on the microfluidic chip, thereby also limiting the density or efficiency of packing of an array of parallel channels.